Methods and compositions for highly purified boron nitride nanotubes

Abstract

Herein we describe purified boron nitride nanotube compositions substantially free from hexagonal boron nitride. The compositions have a mass ratio of boron nitride nanotubes to hexagonal boron nitride of at least 100. Methods are provided for producing said purified boron nitride nanotube compositions wherein impure compositions are subjected to heating with a C 5 to C 11 hydrocarbon solvent under specified conditions.

What is claimed is: 
     
         1 . Purified boron nitride nanotubes having a mass ratio of boron nitride nanotubes to hexagonal boron nitride exceeding 100. 
     
     
         2 . The purified boron nitride nanotubes of  claim 1 , having a BNNT/h-BN X-ray diffraction spectral peak ratio of at least 100. 
     
     
         3 . The purified boron nitride nanotubes of  claim 1 , having a BNNT/h-BN X-ray diffraction spectral peak ratio of at least 100 and lacking a significant Raman spectrum peak in the 1366 cm −1  region. 
     
     
         4 . A method for producing purified boron nitride nanotube compositions comprising the steps of:
 mixing an impure BNNT sample with a hydrocarbon solvent;   heating said mixture of said impure BNNT sample and said hydrocarbon solvent for a period of time; and   separating said hydrocarbon solvent from said BNNT sample;   wherein said step of heating is performed at a temperature within 50° C. of the boiling point of said hydrocarbon solvent,   wherein said heating is performed for a period exceeding five minutes, and   wherein said hydrocarbon solvent comprises one or more hydrocarbons possessing at least five carbon atoms and no more than eleven carbon atoms.   
     
     
         5 . The method of  claim 4 , wherein said hydrocarbon is heated such that its vapor pressure is at least 300 mm Hg, and less than 1,150 mm Hg.